Add LCD library.

Amended to correct some bugs, mainly with an extra enable when sending a byte in
nibble mode.
Remove autogenerated files

This files are autogenerated by MPLAB X.
Moved pin specifications

It makes much more sense to store pin specifications in system.h.
Add routine to play buzzer

Buzzer type was changed from electromechanical beeper to piezoelectric. For it
to work, we have to excite it with a 4 kHz square wave.
Fix small TRISA bug

RA4 is the only output, not RA3. Also, disable weak pull-up on RA3 since WPU is
not supported on that pin.
Small cosmetic changes, add guard on system.h
Disable analog function on pins

We discovered this causes trouble with weak pull-ups.
Add putch() routine

This enables the use of the printf() function in the standard library.

Also, initialize the LCD display on application init.
Disable all LEDs at initialization.
Add self-test routine

The self-test routine lights every available LED and clicks both relays to test
everything.
Read from encoder

Enable interrupt-on-change on RA0 and RA1 to read from encoder. Encoder turns
modify a global counter, which is displayed on the LCD in the main loop.